Art of preparing cellulose films or filaments.



-UNITED STATES PATENT GFFIQE.

FRIEDRICH LEHNER AND ALFRED LEHNER, OF ZURICH, SWITZERLAND.

ART OF PREPARING CELLULOSE FILMS OR FILAMENTS.

SPECIFICATION forming part of Letters Patent No. 724,020, dated March 31, 1903.

Application filed December 27, 1902. Serial No. 136,847. (No specimens.)

T0 otZZ whom it may concern:

Be it known that we, FRIEDRICH LEHNER and ALFRED LEHNER, citizens of Germany, residing at Weinbergstrasse 73, Zurich, Switzerland, have invented certain new and useful Improvements in'the Art of Preparing Cellulose Films or Filaments; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the preparation of films and filaments and the like from cellulose solutions; and the object of the same is to prepare such articles having a colorless glossy appearance in a rapid and industrially practical manner.

As known, the solutions of viscose or cellulose sulfo-carbonate have hitherto been worked into glossy filaments or films by forcing purified viscose solutions through contracted openings into ammonium-chlorid solutions, whereby when the process has been correctly carried out cellulose hydrate is thrown out and precipitated. in the form of colorless films or filaments. This conversion or decomposition by ammonium chlorid is, however, objectionable, for the reason that it progresses very slowly toward the interior of the bodies formed, thereby necessitating a considerable loss of time and high concentration of the ammonium-chlorid solution and a continual regeneration of the same. If this is not done, the filaments break. continually and the process is seriously impeded.

A congealing and hardening agent, which at the same induces a rapid decomposition of the viscose to cellulose hydrate,and therefore will produce a strong filament from the point at which the solution issues into the said congealing liquid, is sulfuric acid,which is, more-- WVe will now describe in detail what WG/COII- sider the preferable manner of carrying out our invention.

A viscose solution, which maybe prepared in any well-known or suitable manner or in caused to issue into a moderately-concentrated sulfuric-acid bath through contracted openings in a manner well known. A film or filament which is turbid or milky white by reason of the sulfur or sulfur compounds existing in the materials operated with is precipi'tated or thrown out, which thread after passing a short distance from the sulfuric acid is wound upon spools, bobbins,or reels outside of this congealing sulfuric-acid bath. These spools, bobbins, or reels when filled are immediately immersed into abath which has the property of eliminating the sulfur or sulfur compound existing in the films or filaments. We find that for this purpose sulfol ydrates, sulfids, sullites, and bisulfites df the alkali add alkaline earths are saturate adapted, desulfurizing the filaments or films completely or to such an extent that they produce a colorless glossy product. These solutions, one, several, or all of which may be used, may be used even in the cold if concentrated. However, we find it more advantageous to heat them to from about to 80 centigrade when acting on the films or fila ments. At this degree of heat even diluted solutions of these bodies will produce a rapid finish or decolorization and glossing of the thread. For example, we find that at between these temperatures an eight-per-cent.

any manner to be hereinafter devised, is

solution of sodium hydrate, ammonium sul- ICO ments from viscose solutions, which consists ing films or filaments from a viscose solution by passing the same through a sulfuric-acid 15 bath and then treating the resultant product with a sulfid hydrate, sulfid and bisulfite of an alkali or alkaline earth.

In testimony whereof we affix our signatures in presence of two witnesses.

FRIEDRICH LEHNER. ALFRED LEHNER.

Witnesses:

A. LIEBERKNECHT, W. RASEHERT. 

